A view from the San Diego county side of the San Onofre Nuclear plant. ANA VENEGAS, FILE: THE ORANGE COUNTY REGISTER

Edison letter: key quotes

Key quotes from 2004 letter sent by Dwight E. Nunn, then-vice president of Southern California Edison, to Mitsubishi Heavy Industries (parentheses are Nunn's):

"This will be one of the largest steam generators ever built for the United States and represents a significant increase in size from those that Mitsubishi Heavy Industries has built in the past."

"... the design of the new steam generators is currently proceeding using the existing steam generator seismic response based on a like-for-like replacement concept (although the old and new steam generators will be similar in many respects they aren't like-for-like replacements)."

"I am concerned that there is the potential that design flaws could be inadvertently introduced into the steam generator design that will lead to unacceptable consequences (e.g. tube wear and eventually tube plugging). This would be a disastrous outcome for both of us and a result each of our companies desire to avoid."

A U.S. senator is using a newly revealed letter to call for a Department of Justice investigation of Southern California Edison, focusing on whether company officials deceived regulators about the replacement of steam generators at the San Onofre nuclear plant.

The steam generators eventually proved defective and have kept the plant shuttered since January 2012. But this week, Sen. Barbara Boxer, D-Calif., released a 2004 letter from an Edison executive that she says reveals "misrepresentations and safety lapses by Edison."

The letter also includes "this kind of eerie prediction" about possible design flaws that could lead to leakage of metal tubes inside the steam generators, Boxer said. A tube leak did, in fact, prompt the shutdown of the plant's Unit 3 reactor on Jan. 31, 2012.

"This was not a low-level person," Boxer said in a telephone news conference. "They knew exactly what they were doing. Any machinations to get out of their own words are just not going to work. It defies common sense and it's embarrassing and you ought to just tell the truth. Start now."

In its own statement, Edison said the letter, and a second from 2005, show that Edison was closely tracking design work by the manufacturer of the steam generators, Mitsubishi Heavy Industries in Japan, "to ensure that design flaws were not inadvertently introduced."

"These documents demonstrate the type of careful oversight that SCE exercised during the replacement steam generator project and also served to establish our expectations of MHI," the statement said, quoting Edison's senior vice president and chief nuclear officer, Pete Dietrich.

Edison said it provided both letters to the Nuclear Regulatory Commission in April. Boxer and her staff declined to say how her office obtained the 2004 letter, and NRC officials declined to comment.

Mitsubishi also declined to comment.

Much of Boxer's concern centers on the idea that Edison considered changes in design of the steam generators to be "like for like" – that is, similar enough to the generators that were being replaced to avoid triggering a higher level of regulatory review.

But the 2004 letter, sent to Mitsubishi by Dwight E. Nunn, then-vice president at Edison, says that while discussing design questions concerning seismicity in the region that "although the old and new steam generators will be similar in many respects they aren't like-for-like replacements."

Design changes included additional tubing and alterations in tube support structures.

"They certified to a like-for-like schematic," Boxer said Tuesday. "It wasn't like for like. You can't do that. You can't lie. You have to tell the truth."

Edison, however, said in a second statement Tuesday that the regulations under which the steam-generator replacement was conducted do not require "like for like" replacements.

"At no time did SCE hide the differences from the NRC, nor did it seek to mislead the NRC concerning the applicability" of the NRC regulatory process, known as Section 50.59.

In a second, key statement, Nunn talks about the possibility of steam-generator tube leaks.

"I am concerned that there is the potential that design flaws could be inadvertently introduced into the steam-generator design that will lead to unacceptable consequences (e.g. tube wear and eventual tube plugging)," the letter says. "This would be a disastrous outcome for both of us and a result each of our companies desire to avoid."

In fact, unusual and premature wear was discovered among the thousands of steam-generator tubes in all four of San Onofre's steam generators, two for each reactor.

Inspections of both reactor units that revealed the tube wear followed the shutdown of Unit 3. Unit 2 had been shut down earlier in January 2012 for routine maintenance.

The tube wear was traced to design flaws in the steam generators that caused excessive vibrations while the generators were operating. One worn tube sprang a leak, leading to release of a small amount of radioactive gas and prompting the Unit 3 shutdown.

The steam generators were installed between 2009 and early 2011 in a $670 million operation.

Edison has requested permission from the NRC to restart its Unit 2 reactor at 70 percent power. Edison officials say that should curb the vibrations believed to have caused the tube wear.

But Boxer and environmental activists, including the group Friends of the Earth, say that investigations of the problems at San Onofre and a required public hearing should take place before any restart decision is made.

"They are telling people this is not a disaster, it's no big deal, we can start up at 70 percent," Boxer said during the news conference. "That's why it's so disturbing."

The California Public Utilities Commission, which is in the midst of its own investigation to determine whether ratepayers should be reimbursed for costs associated with the problems at San Onofre, also expressed concern Tuesday about Boxer's assertions.

The news "appears to be very pertinent to investigations currently under way" at the CPUC and the NRC, the statement says.

"A preliminary review of our records suggests the letters referenced by Senator Boxer were not provided by Edison either to the CPUC itself or to the parties participating in our investigation into the SONGS (San Onofre Nuclear Generating Station) outage," the statement continues.

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